Subitizing in Children and Adults, Depending on the Object Individuation Level of Stimulus: Focusing on Performance According to Spacing, Color, and Shape of Objects

This study investigated the development and core mechanism of subitizing in children and adults as well as provides related theoretical and practical discussions. This study was conducted to determine if subitizing changed with the age of participants and if there were differences in subitizing according to the spacing, color, and shape of the stimuli. The subitizing task set (including forty main trials) was prepared. Forty-five children (fifteen each in groups of 3, 4, and 5-year-olds) and fifteen adults were recruited to perform the subitizing tasks. The results demonstrated that the subitizing speed and accuracy of children improved abruptly between age 3 and age 4. Furthermore, there were significant differences in children’s subitizing speed according to the spacing and color of the objects. The children’s response time decreased when the objects were fully apart or were of diverse colors. In addition, there were partial significant differences in the subitizing speed of children related to the shape of the objects. The subitizing speed of children decreased in a condition (subitizing 5 objects of diverse colors in fixed spacing) when the shapes of the objects were diverse. The subitizing speed of adults only differed according to the space of the objects. The results demonstrate the development of subitizing in early childhood along with the presence of object individuation processing stages underlying subitizing. This study also provides practical information and suggestions for educational curricula that can strengthen the competency of children in systematic and diverse activities. Keywords: subitizing, parallel individuation of objects, perceptual properties of stimulus, enumeration in children